cat-file: fix a memory leak in --batch-command mode

cat-file: fix a memory leak in --batch-command mode

Fix a memory leak introduced in 440c705ea63 (cat-file: add
--batch-command mode, 2022-02-18). The free_cmds() function was only
called on "queued_nr" if we had a "flush" command. As the "without
flush for blob info" test added in the same commit shows we can't rely
on that, so let's call free_cmds() again at the end.

Since "nr" follows the usual pattern of being set to 0 if we've
free()'d the memory already it's OK to call it twice, even in cases
where we are doing a "flush".

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>